Health

Child Height Predictor

Estimate your child's adult height using the mid-parental method.

Child Sex

Mother Height

Father Height

Unit

Predicted Adult Height

178.0 cm

Mid-parental method

Range ± 8.5 cm (or ± 3.3 in). Genetics vary; actual height may differ.

Predicted Range169.5 – 186.5

Mother Height165.0

Father Height178.0

What is the Child Height Predictor?

The child height predictor is a genetics-based calculator that uses the mid-parental height formula to estimate a child's adult height. It takes the average of both parents' heights and applies a sex-specific adjustment: boys gain 13 cm and girls lose 13 cm. The result is a reliable prediction with a margin of error, acknowledging that nutrition, exercise, and other environmental factors also influence final height.

How it works

The calculator applies the mid-parental height formula: for boys, (father's height + mother's height + 13 cm) ÷ 2; for girls, (father's height + mother's height − 13 cm) ÷ 2. The 13 cm adjustment reflects the average biological difference in growth patterns between sexes. The tool then displays a range of ±8.5 cm around the predicted height, representing the typical margin of variation due to genetics and environment.

Boys: (Father's Height + Mother's Height + 13 cm) ÷ 2; Girls: (Father's Height + Mother's Height − 13 cm) ÷ 2

The mid-parental height formula is derived from twin studies and family genetic research. It assumes that parental height accounts for roughly 80% of a child's adult height. The ±13 cm sex-based adjustment comes from epidemiological data showing that boys are on average taller than girls. The ±8.5 cm margin accounts for the remaining 20% of variation due to nutrition, illness, exercise, and other non-genetic factors.

Examples

Input	Result	Notes
Boy with 165 cm mother and 180 cm father	173.5 cm (5'8.5") ± 8.5 cm	Formula: (180 + 165 + 13) ÷ 2 = 179 cm. The child is likely to fall between 165 cm and 188 cm, with 179 cm as the best estimate.
Girl with 160 cm mother and 175 cm father	166 cm (5'5.3") ± 8.5 cm	Formula: (175 + 160 − 13) ÷ 2 = 161 cm. The child is likely to fall between 152.5 cm and 169.5 cm.
Boy with 5'6" mother and 5'11" father	5'10.5" (178 cm) ± 8.5 cm	Heights can be entered in feet and inches. The tool converts internally and displays results in both units.

How to use the Child Height Predictor

Select your child's sex: Boy or Girl.

Enter your child's mother's height in cm or feet & inches.

Enter your child's father's height in the same unit.

Choose your preferred output unit (cm or feet & inches).

The tool instantly calculates the predicted adult height and range.

Review the predicted height and the ±8.5 cm range for context.

Benefits

Based on proven genetics research—the mid-parental method has strong clinical backing.

Quick and free—no sign-up or complicated inputs required.

Shows both a single estimate and a realistic range, not false precision.

Accounts for sex-specific growth patterns using the 13 cm adjustment.

Works in metric (cm) or imperial (feet & inches) units.

Useful for paediatricians, parents, and growing children to set realistic expectations.

Tips & common mistakes

Common mistakes

Entering only one parent's height—the formula requires both mother and father heights to work.

Confusing predicted height with guaranteed height—genetics account for ~80%; nutrition, health, and activity level matter too.

Forgetting to account for the ±8.5 cm range—the prediction is a best estimate, not exact.

Using future or estimated parent heights instead of their actual adult heights—use measured heights only.

Tips

Use measured heights, not guesses; a 5 cm error in parental height shifts the prediction by 2.5 cm.

Remember the ±8.5 cm range accounts for variation; most children fall within this band.

If both parents are outliers (very tall or very short), the prediction may be less accurate; genetic diversity plays a role.

Track growth over time using a growth chart app; sustained deviations from the prediction may warrant a paediatrician visit.

Frequently asked questions

Is the mid-parental height formula accurate?

Yes, studies show it predicts adult height within ±8.5 cm for 68% of children and ±17 cm for 95% of children. It's one of the most reliable non-invasive methods, though environmental factors (nutrition, sleep, exercise) can shift the outcome.

Why is there a 13 cm adjustment for boys and girls?

On average, boys are about 13 cm taller than girls due to testosterone-driven growth during puberty. This adjustment reflects population-level biological sex differences. Individual variation is always possible.

What if the parents are very tall or very short?

The formula still applies, but tall or short parents will have taller or shorter children on average. However, regression to the mean occurs—children of extremely tall parents are often slightly shorter than their parents, and vice versa.

Does nutrition or exercise affect the prediction?

Genetics determines the height ceiling; nutrition and exercise help a child reach their genetic potential. Poor nutrition or chronic illness can reduce final height by several centimetres. The ±8.5 cm range captures some of this variation.

Can I predict a child's height if I'm their step-parent or adoptive parent?

Use the biological parents' heights for accuracy. If you don't know them, the prediction cannot be reliably calculated, as genetics from unknown parents introduces too much uncertainty.

At what age is this prediction most accurate?

The mid-parental method is most accurate after age 3, when most children have passed early growth fluctuations. It becomes more reliable with each year and is fully valid by late childhood (around age 8–9).